Missing @required arg quick fix improvements.

pkg/analysis_server/lib/src/services/correction/fix.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analysis_server.src.services.correction.fix;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/edit/fix/fix_core.dart';
 import 'package:analysis_server/src/plugin/server_plugin.dart';
@@ skipping 106 matching lines @@
       const FixKind('ADD_ASYNC', 50, "Add 'async' modifier");
   static const ADD_FIELD_FORMAL_PARAMETERS = const FixKind(
       'ADD_FIELD_FORMAL_PARAMETERS', 30, "Add final field formal parameters");
   static const ADD_MISSING_PARAMETER_POSITIONAL = const FixKind(
       'ADD_MISSING_PARAMETER_POSITIONAL',
       31,
       "Add optional positional parameter");
   static const ADD_MISSING_PARAMETER_REQUIRED = const FixKind(
       'ADD_MISSING_PARAMETER_REQUIRED', 30, "Add required parameter");
   static const ADD_MISSING_REQUIRED_ARGUMENT = const FixKind(
-      'ADD_MISSING_REQUIRED_ARGUMENT', 30, "Add required argument");
+      'ADD_MISSING_REQUIRED_ARGUMENT', 30, "Add required argument '{0}'");
   static const ADD_NE_NULL = const FixKind('ADD_NE_NULL', 50, "Add != null");
   static const ADD_PACKAGE_DEPENDENCY = const FixKind(
       'ADD_PACKAGE_DEPENDENCY', 50, "Add dependency on package '{0}'");
   static const ADD_SUPER_CONSTRUCTOR_INVOCATION = const FixKind(
       'ADD_SUPER_CONSTRUCTOR_INVOCATION',
       50,
       "Add super constructor {0} invocation");
   static const CHANGE_TO = const FixKind('CHANGE_TO', 49, "Change to '{0}'");
   static const CHANGE_TO_STATIC_ACCESS = const FixKind(
       'CHANGE_TO_STATIC_ACCESS', 50, "Change access to static using '{0}'");
@@ skipping 105 matching lines @@
   @override
   final AnalysisError error;
 
   FixContextImpl(this.resourceProvider, this.analysisContext, this.error);
 
   FixContextImpl.from(FixContext other)
       : resourceProvider = other.resourceProvider,
         analysisContext = other.analysisContext,
         error = other.error;
 }